Unfair customer treatment.

Bidorbuy and cashconverters took my money. I paid to bidorbuy wrongly withouth their ref number but they said they give my money to cashconverters, since last year october both of them are failing to refund me, i paid bidorbuy and they said i must claim from cashconverters, how come? Isn't it that bidorbuy must pay back my money and cashconverters pay back bidorbuy's money?